feat(3dtiles): add support for 3d tiles from cesium ion server

src/Layer/C3DTilesLayer.js

@@ -13,7 +13,7 @@ class C3DTilesLayer extends GeometryLayer {
      * @extends GeometryLayer
      *
      * @example
-     * // Create a new Layer 3d-tiles For DiscreteLOD
+     * // Create a new 3d-tiles layer from a web server
      * const l3dt = new C3DTilesLayer('3dtiles', {
      *      name: '3dtl',
      *      source: new C3DTilesSource({
@@ -22,6 +22,16 @@ class C3DTilesLayer extends GeometryLayer {
      * }, view);
      * View.prototype.addLayer.call(view, l3dt);
      *
+     * // Create a new 3d-tiles layer from a Cesion ion server
+     * const l3dt = new C3DTilesLayer('3dtiles', {
+     *      name: '3dtl',
+     *      source: new C3DTilesIonSource({
+     *              accessToken: 'myAccessToken',
+                    assetId: 12
+     *      })
+     * }, view);
+     * View.prototype.addLayer.call(view, l3dt);
+     *
      * @param      {string}  id - The id of the layer, that should be unique.
      *     It is not mandatory, but an error will be emitted if this layer is
      *     added a

src/Main.js

@@ -76,6 +76,7 @@ export { default as VectorTilesSource } from 'Source/VectorTilesSource';
 export { default as OrientedImageSource } from 'Source/OrientedImageSource';
 export { default as PotreeSource } from 'Source/PotreeSource';
 export { default as C3DTilesSource } from 'Source/C3DTilesSource';
+export { default as C3DTilesIonSource } from 'Source/C3DTilesIonSource';
 export { default as EntwinePointTileSource } from 'Source/EntwinePointTileSource';
 
 // Parsers provided by default in iTowns

src/Source/C3DTilesIonSource.js

@@ -0,0 +1,60 @@
+import Fetcher from 'Provider/Fetcher';
+import C3DTilesSource from './C3DTilesSource';
+
+/**
+ * @classdesc
+ * An object defining the source connection to a 3DTiles asset of a [Cesium ion server](https://cesium.com/learn/ion/).
+ *
+ * @extends Source
+ *
+ * @property {boolean} isC3DTilesIonSource - Used to checkout whether this source is a C3DTilesIonSource. Default is
+ * true. You should not change this, as it is used internally for optimisation.
+ * @property {string} url - The URL of the tileset json.
+ * @property {string} baseUrl - The base URL to access tiles.
+ * @property {string} accessToken - The Cesium ion access token used to retrieve the resource.
+ * @property {string} assetId - The id of the asset on Cesium ion.
+ */
+class C3DTilesIonSource extends C3DTilesSource {
+    /**
+     * Create a new Source for 3D Tiles data from Cesium ion.
+     *
+     * @constructor
+     * @extends Source
+     *
+     * @param {Object} source An object that can contain all properties of a C3DTilesIonSource and {@link Source}.
+     * Only `accessToken` and `assetId` are mandatory.
+     */
+    constructor(source) {
+        if (!source.accessToken) {
+            throw new Error('New 3D Tiles Ion Source: access token is required');
+        }
+        if (!source.assetId) {
+            throw new Error('New 3D Tiles Ion Source: asset id is required');
+        }
+
+        // Url to query cesium ion the first time to retrieve metadata of the asset with assetId
+        source.url = `https://api.cesium.com/v1/assets/${source.assetId}/endpoint?access_token=${source.accessToken}`;
+        super(source);
+
+        this.isC3DTilesIonSource = true;
+        this.accessToken = source.accessToken;
+        this.assetId = source.assetId;
+
+        // get asset metadata
+        this.whenReady = Fetcher.json(source.url, this.networkOptions)
+            .then((json) => {
+                if (json.type !== '3DTILES') {
+                    throw new Error(`${json.type} datasets from Cesium ion are not supported with C3DTilesIonSource. ` +
+                    'Only 3D Tiles datasets are supported.');
+                }
+                this.url = json.url; // Store url to the tileset.json
+                this.baseUrl = json.url.slice(0, json.url.lastIndexOf('/') + 1); // baseUrl for tiles queries
+                this.networkOptions.headers = {};
+                this.networkOptions.headers.Authorization = `Bearer ${json.accessToken}`;
+                this.attribution = json.attributions;
+                return Fetcher.json(this.url, this.networkOptions);
+            });
+    }
+}
+
+export default C3DTilesIonSource;